Regenerative liquid fuel rocket motor



Aug. 17, 1954 R. J. ANDRUs REGENERATIVE LIQUID FUEL ROCKET MOTOR FiledJuly 12, 1948 3 Sheets-Sheet l Aug. 17, 1954 R. J. ANDRus 2,686,400

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Patented Aug. 17, 1954 REGENERATIVE LIQUID FUEL ROCKET MOTOR Rodney J.Andros, Berkeley, Calif., assigner to the United .States of America asrepresented by lthe Secretary of the Air Force Application July 12,1948, Serial No. 38,315

4. Claims.

The invention described herein may be manufactured and used by or forthe Goverment for governmental purposes without payment to me of anyroyalty thereon.

This invention relates to rocket motors, more particularly to rocketmotor propulsion devices utilizing liquid fuel propellants andoxidizers, having for one of its objects the provision of improvedliquid propellant and coolant circulation means for controlling thetemperature of the walls of the combustion chamber and heating theiiquid propellant before it is burned therein.

A still further object is the provision in a rocket motor having aninner shell formed with a combustion chamber having a constricteddischarge nozzle, or" a helically arranged supporting means on theexterior of the inner shellv extending from end to end to space andsupport an outer shell thereon with the inner wall of the outer shell incontact with the helical supporting means throughout its length, andmeans for rigidly connecting the inner shell to the outer shell at thedischarge end of the discharge nozzle to secure the open ends of theshells together, and including slidable expansion joint means at theother ends of the shells for supporting the inner shell concentricallywithin the outer shell for relative axial expansion movementtherebetween.

Another object of the invention is the provision in a rocket motorhaving an inner shell formed with a tubular combustion chamber and anintegral constricted discharge nozzle extending rearwardly therefrom, ofhelically arranged supporting, reinforcing and heat dissipating means onthe outer surface of the inner shell, extending from the dischargenozzle at the rear end to the front end of the combustion chamber, andtubular supporting means disposed around the exterior of the constrictednozzle portion in spaced relation thereto, with the helical supportingmeans slidable disposed in supporting contact with the interior of thetubular supporting means and the interior of an outer enclosing shell,and including slidable packing and liquid sealing means between thetubular supporting means and the interior of the outer shell, whereby aliquid coolant fuel or propellant may be introduced between the outershell and inner shell adjacent tlie rear end of the discharge nozzle oithe inner shell and circulated helicallyV around the discharge nozzleand combustion chamber to the front end of the combustion chamber tocool the saine, having meansl for introducing the coolant in a heatedconditioninto the combustion chamber at its forward end.

Other objects and advantages of the invention will become apparent fromthe following description, taken in connection with the accompanyingdrawings, in which like reference characters refer to like parts in theseveral figures.

Fig. 1 is a side elevation of one form of my improved rocket motorconstruction, a portion of the inner and outer shell being broken awayand shown in section.

Fig. 2 is a side elevation, partly broken away and shown in section, ofa slightly modied form of my improved rocket motor.

Fig. 3 is a side elevation, partly broken away and shown in section, ofthe further modified embodiment of my invention.

Fig. 4 is a fragmentary detail View of the locking key member andcooperating notches in the channel and slots in the follower ring.

Referring more particularly to Fig. 1 of the drawings the referencenumeral I indicates the hollow cylindrical outer shell of a liquidpropellant rocket motor, closed at its forward end by a rounded head 2,welded thereon at 2a. The rear end of the outer shell l is open andformed with an external flange 3. An inner shell is disposed within theouter shell I in spaced relation thereto and provided with a roundedhead portion 5 welded thereto at 5a, the exterior curvature of the head5 following the approximate interior curvature of the head 2. The rearor discharge end of the inner shell 4 has an outwardly extending flange6 formed thereon which overlies the rear face of the external ange 3 ofthe outer shell l and the inner and outer shells are secured together bythe flanges 3 and 6 through suitable fastenings such as the studs orbolts 6a, 6a as shown in the drawing. The inner shell 4 includes acombustion chamber l having a constricted discharge nozzle portion 8extending rearwardly therefrom with the annular flange 6 formed on theshell 4 at the rear end of this discharge nozzle 8. The constrictedportion of the discharge nozzle 8 is surrounded by a longitudinallysplit, as indicated by dotted line 9a, tubular supporting member orfiller block 9, guidingly supported by the interior surface of the outershell as clearly seen in the drawings. The two half sections of thefiller block may preferably be secured together by any suitable means(not shown), and is formed with an external annular channel l0, in whichsuitable liquid sealing packing ring means Il is disposed. A followerring l2 is suitably threaded on thev exterior threaded portion of theliller block 9, and is rotatable to expand the packing Il. This followerring I2 may be also split longitudinally so that it can be easilyslipped over the filler block and secured together in the channel Ill inengagement with the threaded portion of the filler block 9. The followerring I2 may be provided with radial wrench slots I3 around its peripheryand suitably conforming ccmplemental radial locking notches I l may beprovided in the channel I8 opposite the slots for inserting the oppositeends of a locking key I5 in the notches and wrench slots I 4 to lock thering i2 against rotation on the filler block S, as shown in Fig. 4.

The packing II is preferably expanded into sealing engagement with theinterior surface of the outer shell I before the inner shell is forcedits full distance into the outer shell. The packing II is compressed `byrst introducing the inner shell il into the outer shell I sufficientlyto bring the packing II within the confines of the interior of the outershell without covering the wrench slots I3, the packing I being held inplace by the outer shell, the ring I2 being rotated in the correctdirection to compress the packing II against the interior of the outershell. After the packing II has been compressed the locking key i5 isinserted with the opposite ends in one of the registering notches Illand wrench slots I3 and the inner shell f: is then forced into the outershell I to its fullest extent, to the position shown in Fig. l of thedrawings.

The outer surface of the inner shell l is provided with one or morespiral or helical webs or ribs I6 which extend from the discharge nozzleend of the inner shell along the entire length of the discharge nozzleand the combustion chamber in conformity therewith and terminate at thehead portion 5. At the discharge end of the outer shell I of the motoran intake port and fitting Il is provided for supplying a liquidcoolant, preferably a propellant component, between the inner and outershells ll and I, especially to the walls of the inner shell and directthis liquid coolant helically around the discharge nozzle and thecombustion chamber to the forward end of the inner shell.

A hollow stem member I8 is formed on the i forward end of the innershell 4 on its rounded head or closure 5 and projects through the headof the outer shell, a slidably sealing connection therebetween beingprovided by a packing gland I9, permitting relative axial expansivemovement between the inner and outer shells 2. The space between theheads 2 and 5 of the shells I and 4 denes a liquid fuel injectionchamber 29 having a plurality of fuel injection ports 2I directed intothe combustion chamber 'I. is formed with a central injection chamber 22into which a suitable fitting 23 is secured for introducing a secondpropellant component into the chamber 22, such as a liquid oxidizer,complementary to the component circulated between the walls of theshells I and 4. The injection chamber 22 is provided with a concentricring of inlet ports 24, so positioned that the streams of the fuel andthe oxidizer issuing from the ports 2| and 2li impinge each other.

The outer or peripheral portion of the helical web or rib I 6 isdisposed to rest against the interior of the outer shell throughout themajor portion of its length and the portion of the helical web extendingaround the discharge nozzle is disposed in contact with the filler block9 so as to support the inner shell 13 and discharge nozzle throughoutits entire length, providing a heat exchanging rib which constitutes thewall of a helical fluid circulation passage whereby the liq- The hollowstem I8 uid coolant and propellant fuel component is directed helicallyaround the inner shell, effecting a satisfactory cooling of the innershell and heating of the coolant liquid before it enters the injectionchamber 20, and is introduced in the combustion chamber I with the otheror oxidizer liquid.

The packing gland I9 permits relative expansion and axial movement ofthe inner shell 4 with respect to the outer shell I, the packing IIaround the filler block 9 allowing the filler block to move axiallywithin the outer shell to accommodate the axial movement of the nozzle 8relative to the outer shell I, due to expansion or contraction, whilepreventing the flow of the coolant liquid between the filler block 9 andthe interior of the outer shell I.

The spirally arranged rib on the exterior of the inner shell d makes itpossible to form this shell with a somewhat thinner wall section, thehelical rib also constituting helical reinforcing means for thecombustion chamber and for supporting the entire shell in concentricallyspaced relation to the outer shell and to the filler block, effecting aheat transfer from the combustion chamber I and discharge nozzle 8 tothe helical rib IE, this heat being satisfactorily dissipated by therapid helical circulation of the coolant fuel from the intake fitting I?to the injection chamber 20. This coolant fuel is correspondingly heatedby the exterior of the combustion chamber 'I to produce bettercombustion as it enters the combustion chamber 'I and is mixed with theoxidizer for component fuel.

Referring to Fig. 2 the outer shell is indicated at I' having a head 2and an external flange 3'. The inner shell 4 is formed with a head 5 atone end and a supporting flange G at the other end secured in positionby suitable fasteners such as studs or bolts Ga. The inner shell isformed with an elongated combustion chamber 'I' having a restricteddischarge nozzle I8 extending rearwardly therefrom and surrounded by alongitudinally split tubular follower block or ring 9 somewhat similarto the construction shown in Fig. 1. The follower ring 9' is providedwith the annular channel I0 in which a packing ring gland or seal II isdisposed. The threaded follower ring I2 is preferably provided withradial wrench slots I3' for tool engagement in tightening the ring I 2'to expand the packing I 0 into engagement with the interior of the outershell as explained in connection with Fig. l. In this form of theinvention the helical fluid circulating and cooling web or rib isindicated at I6 and projects from the outer surface of the combustionchamber portion of the inner shell, extending from a point near theforward end of the discharge nozzle 8' to the head of the combustionchamber l. The tubular filler block El', split longitudinally as at 9a',is provided as in the construction in Fig. l, but with a helical rib I6"which extends helically in the same direction as the helical rib I6projecting from the outer surface of the combustion chamber, to providea continuous helical fluid conduit with the helical rib I6, around theexterior discharge nozzle 8 and the combustion chamber i", from thecoolant and propellant intake port I'I at the rear end of the motor toan injection chamber 2D' at the forward end.

The forward end of the inner sleeve 4' is formed with a tubularsupporting extension I8', slidably received in a guide opening I8",formed inthe forward end of the outer shell I. .Asomevfuel or oxidizerdelivered from a suitably supply fitting 23', injection of the componentfuel being made into the combustion chamber l through injection ports24" which are disposed, with respect to ports 2l', so that the streamsof the fuel and the oxidizer from the chambers and 22' are directedrearwardly and towards each other in' the combustion chamber 1', asshown by the arrows in the drawings. A packing gland I9 is seated in anannular channel formed in the tubular extension i8', a suitable packingnut I9" being provided and threaded on the end of the tubular extensionI8' as shown in Fig. 2 of the drawings, so as to expand the packing i9.The fitting 23 is secured in place in a threaded tubular bore formed inthe hollow stem I8 by a threaded locking sleeve or collar 23 whichengages a flanged end 23a formed on the inner end of the fitting 23' asshown in Fig. 2.

The coolant and propellant liquid is introduced between the inner andouter sleeves 4 and I at the rear end of the outer sleeve through theintake port ll and is conducted helically around the discharge nozzle 8and the combustion chamber l by the helical rib portions i6" and I6',effecting a heat transfer between the liquid and the outer surface ofthe discharge nozzle 8 and the combustion chamber l', the coolant fuelbeing delivered into the injection chamber 20 in a heated condition isthen injected through the ports 2l into the front end of the combustionchamber l and is burned, combustion being supported by the cxidizer orother component propellant liquidthat is introduced through the tting 23and injected into the combustion chamber 1' through the ports 24. Thehelical arrangement of the supporting rib or web It provides excellentheat transfer means and also supports and reinforces the inner sleeve 4'concentrically within the outer sleeve l throughout its length. Thetubular extension i8 with its liquid sealing packing gland I9 maintainsthe forward end of the inner sleeve fl concentric within the outersleeve l and permits relative axial expansion between the forwardportions of the inner and outer sleeves Il and without leakage.

In Fig. 3 a somewhat different arrangement is provided although thehelical reinforcing rib and coolant fuel circulation conduit meansbetween the inner and outer shells is somewhat similar to the otherforms of my invention as described. in conjunction with Figures l and 2,provisions also being made for expansion between. the inner and outershell members and the prevention of leakage of. the helically circulatedcoolant fuel at the points of expansion. Theinner cylindrical. shellmember is indicated at El having a combustion chamber 32, with adischarge nozzle 33 welded to the rear end of the inner shell at 3d. Therear endof the discharge nozzle ig provided with an annular flange 34;and the forward end of the inner shell 3l is provided with an annularsupporting plate or ilange 35 integrally secured thereto by welding. Theouter cylindrical shell 36 is welded or otherwise secured to the annularplate or flange 35 to secure the inner and outer shells 3| and 35together on this-:platelor flange.

Bolted and sealed to the rear flange 34 ofthe discharge nozzle is atubular counter-boredcollar 3l extending forwardly in telescopicrelationto the rear end of the outer shell 3'6. An O'ring or suitable sealinggasket 38 is seated inanannular internal channel in the collar 3landseals the space between the exterior of the outer shell'y 36 and theinternal bore of the collar 3l. The space between the outer shell 3B andthe exterior ofthe constricted discharge nozzle contains atubular fillerblock or supporting ring 39 which is split longitudinally as indicatedat tllir for assembly purposes and may be suitably secured togethersimilar to the ller block 9 or il described in connection with the formof .my invention illustrated in Figs. l and 2. An O-ring or packing 4l)is seated in an annular channel in the ller block 39, sealing the spacebetween the interior of outer shell 35 and the exterior of thefil1er.block.39, permitting the inner shell 3l and its nozzle 33 toexpand and move axially together with. the filler block 3S, relative tothe outer shell 3S. The outer surface of the inner shell 3l is providedwith one or more helical ribs or webs All whichfollow the outer contourof the discharge nozzle 33 and the outer surface of the walls of thecombustion chamber 32, extending between the flanges 34 and 35. rhe ribil provides a helical conduit or passage from the rear end of the outershell 36 to the forward end of the inner shell. 3|, between the shells.An inlet port and iitting 42 is provided connecting the space betweenthe shells, for introducing a coolant fuel into the helical conduitformed by the helical web fil. Adjacent the forward flange 35 theconduit between the helical rib :li communicates with an annular chamberda having outlet ports or nozzles M secured in an annular rib Q3, in theforwardls7 dii/erging conical face thereof.

The forward end or" the motor is closedv by a head de having an integralflange itl which is bolted to the flange 35. The head 115 is providedwith conforming spaced inner and outer walls @l and 48, defining betweenthem a collection chamber iii). Suitable injection nozzles 5E aremounted inthe head lil in communication with the collection chamber leto direct the propellant component or oxidizer introduced through thefitting QS', into streams or jets which impinge the streams or jets ofthe component propellant issuing from the injection nozzles e4.

In this forni of the invention the two propellants or the propellant andthe oxidizer are conducted around the exterior of the inner shellbetween the saine and the outer shell from their respective inletfittings [l2 and It at least one of the propellants being conductedhelically around the combustion chamber of the inner shell from itsdischarge nozzle toward the flange portion l5-le The dange or annularplate members 35 and it constitute a rigid support for the rocket motor.Elongated securing bolts maybe provided as shown, so as to provide boltfastening means passing through the flanges and a supporting frame 55which is apertured at 5l to receive the mixing and combustion chamberhead 48 therethrough. Expansion between the inner and outer shells isprovided, without leakage, by the telescopic collar 3l and the ringsealing gaskets 38 therein.

Iclaiin:

l. In a rocket motor, inner and outer spaced concentric cylindricalshells closed at their for.-

ward ends and open at their rear ends, flanged sealing means on theinner and outer shells at their rear ends securing the shells rigidlytogether in concentric relation to close the space between the inner andouter shells, said inner shell having a relatively thin wall between itsends defining an elongated combustion chamber and a constricteddischarge nozzle extending rearwardly therefrom through the outer shell,a helical rib formed integrally on the exterior of the inner shell withits convolutions surrounding said combustion chamber and constricteddischarge nozzle with the outer edge of the rib in contiguous relationto the inner surface of the outer shell to reinforce the inner shellthroughout the length of the combustion chamber and constricteddischarge nozzle and provide a helical liquid coolant fuel conductingpassage between the shells and around the constricted discharge nozzleand the combustion chamber from the rear end of the discharge nozzle tothe forward end of the cornbustion chamber, means for introducing acoolant liquid fuel between the shells at the flanged ends of theshells, coolant liquid fuel inlet means through the forward end of thecombustion chamber in communication with the space between the shellsforwardly of the forward end of the helical rib, a concentricallydisposed tubular extension projecting forwardly from the forward end ofthe combustion chamber, through the forward end of the outer shell, saidouter shell hav ing an end wall closure at its forward end formed with aconcentric guide opening therein slidably receiving and concentricallysupporting the inner shell within the outer shell at its forward end forrelative expansive movement between the shells, said tubular extensionhaving a conduit therethrough in communication with the interior of thecombustion chamber for introducing a liquid fuel oxidizer component,through said extension into the forward end of the combustion chamber tosupport the combustion of the liquid coolant fuel within the combustionchamber, and annular liquid sealing means between the tubular extensionand the guide opening to seal the space between the tubular extensionand the guide opening.

2. In a rocket propulsion motor, an outer cylindrical shell, an innershell concentrically disposed within the outer shell in spaced relationthereto and formed with a combustion chamber having a rearwardlydiverging constricted discharge nozzle, an integral helical ribextending substantially continuously around the exterior of the innershell from a point adjacent the discharge end of the discharge nozzle tothe head of the combustion chamber, an end wall closure for the forwardend of the outer shell having a central guide opening therethrough, anaxial extension extending forwardly from the inner shell through theguide opening in contiguous slidable relation thereto, liquid sealingmeans between said extension and said guide opening to provide forrelative axial expansion between the inner and outer shells, liquid fuelconducting and delivery means between the space between the inner andouter shells at their forward end and the interior of the combustionchamber, conduit means between the exterior of the outer shell and thespace between the inner and outer shells at their rear ends 'forintroducing a liquid coolant fuel thereinto,

for delivery to the interior of the combustion chamber through theliquid fuel conducting means, reinforcing filler block means surround-'ing the-constricted portion of said discharge nozzle in contiguousrelation to the portion of the outer edge of said helical ribsurrounding said discharge nozzle, and slidably disposed within theouter shell in contiguous relation to its inner surface.

3. In a rocket motor, inner and outer concentrically spaced cylindricalshells of relatively thin cross section having their rear ends open, andtheir forward ends closed and spaced to form a. first luid collectionchamber therebetween, said inner shell having an elongated cylindricalcornbustion chamber formed therein with a constricted discharge nozzleextending therefrom through the outer shell and a closed second iiuidcollection chamber at its forward end in communication with the interiorof the combustion chamber; a helical rib integrally formed on theexterior of the inner shell through its length with the convolutions ofthe rib encircling said combustion chamber and discharge nozzle withoutinterruptions therein, with the outer edge of the rib in contiguousrelation to the interior of the outer shell throughout the length of thecombustion chamber; a tubular filler block having a constricted boretherethrough surrounding the -discharge nozzle in contiguous relation tothe outer edge of the helical rib throughout the major portions of thelength of the discharge nozzle; said ller block having its peripherydisposed in contiguous sliding relation to the cylindrical interior ofthe outer shell; annular laterally projecting overlapping ange means onthe rear ends of the inner and outer shells, rigidly securing the shellstogether at their rear ends and closing the space between the rear endsof the inner and outer shells; said inner shell having openingstherethrough at its forward end surrounding the second iiuid collectionchamber in communication between the first fluid collection chamber andthe interior of the combustion chamber; a rst propellant supply conduitconnected to the rst fluid collection chamber at its rear end incommunication with the space between the helical ribs; a secondpropellant supply conduit connected to the second propellant supplychamber and extending forwardly through the forward end of the outershell and comprising an axially disposed tubular support projectingforwardly from the front end of the inner shell; said outer shell havinga guide opening in its front end to slidably receive the tubular supporttherethrough; and fluid tight packing means between the surroundingguide opening and the tubular support in sealing engagement with thetubular support to prevent leakage between the guide opening and thetubular support.

4. Apparatus as claimed in claim 2, including annular liquid sealingmeans between the exterior of the reinforcing filler block means and theinterior of the outer shell, in which said axial extension iscylindrical and projects axially through the central guide openingformed in the closed end of the outer shell.

References Cited. in the file of this patent UNITED STATES PATENTSNumber Name Date 1,879,186 Goddard Sept. 2'7, 1932 2,500,334 Zucrow Mar.14, 1950 OTHER REFERENCES Astronautics for March 1936, pages l2, 13 and18.

Rocketry by C. P. Lent, published by Pen-Ink Pub. Co., W. 42nd Street,New York, N. Y.,

